Arthroplasty instruments and associated method

ABSTRACT

A reamer for use in performing arthroplasty includes a first cutting structure having an inner concave surface that defines a first cavity and terminates in a generally circular leading edge. The inner concave surface includes a first cutting feature that is spaced apart from the leading edge. An elongate member extends from the first cutting structure into the first cavity toward the leading edge that includes a second cutting feature. A second cutting structure is secured to the elongate member and positioned within the first cavity. The second cutting structure extends outwardly from the elongate member toward the inner concave surface and includes a third cutting feature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.10/403,710 entitled “Arthroplasty instruments and associated method”filed Mar. 31, 2003 (now U.S. Pat. No. 8,366,713 issued Feb. 5, 2013),the disclosure of which is hereby incorporated by reference herein inits entirety. Cross reference is also made to the followingapplications: Ser. No. 10/403,707 entitled “ARTHROPLASTY SIZING GAUGE”(now U.S. Pat. No. 7,527,631 issued May 5, 2009), Ser. No. 10/403,750entitled “ARTICULATING SURFACE REPLACEMENT PROSTHESIS” (now Abandoned),Ser. No. 10/403,577 entitled “MODULAR ARTICULATING SURFACE REPLACEMENTPROSTHESIS” (now Abandoned), Ser. No. 10/403,708 entitled “EXTENDEDARTICULATION ORTHOPAEDIC IMPLANT AND ASSOCIATED METHOD” (now U.S. Pat.No. 7,517,364 issued Apr. 14, 2009), and Ser. No. 10/403,365 entitled“PROSTHETIC IMPLANT, TRIAL AND ASSOCIATED METHOD” (now U.S. Pat. No.7,526,527 issued Apr. 28, 2009), which were each filed Mar. 31, 2003 andthe disclosures of which are hereby incorporated by reference herein intheir entirety.

TECHNICAL FIELD

The present disclosure relates generally to the field of orthopaedics,and more particularly, to implants and instruments for use inarthroplasty.

BACKGROUND

There are known to exist many designs and methods for implantingimplantable articles, such as bone prostheses. Such bone prosthesesinclude components of artificial joints, such as elbows, hips, knees andshoulders. An important consideration in the design and implanting ofvirtually any implantable bone prosthesis is that the bone have adequatefixation when implanted within the body.

Earlier designs of implantable articles relied upon the use of cement,such as polymethylmethacrylate (PMMA) to anchor the implant. The use ofsuch implants can have some advantages, such as providing a fixationthat does not develop free play or does not lead to erosion of joiningfaces postoperatively. However, the current trend is to use the cementsto a lesser extent because of their tendency to lose adhesive propertiesover time and the possibility that cement contributes to wear debriswithin a joint.

Recently, implantable bone prostheses have been designed such that theyencourage the growth of hard bone tissue around the implant. Suchimplants are often implanted without cement and the bone grows aroundsurface irregularities, for example, porous structures on the implant.

One such implantable prosthesis is a shoulder prosthesis. During thelifetime of a patient, it may be necessary to replace the naturalhumeral head and associated glenoid cavity with a prosthesis. Such ashoulder replacement procedure may be necessary to be performed on apatient as a result of, for example, disease or trauma, for example,disease from osteoarthritis or rheumatoid arthritis.

Most shoulder replacement surgeries today involve the implantation of atotal shoulder prosthesis. In a total shoulder replacement procedure, ahumeral component having a head portion is utilized to replace thenatural head portion of the upper arm bone or humerus. The humeralcomponent typically has an elongated intramedullary stem which isutilized to secure the humeral component to the patient's humerus. Insuch a total shoulder replacement procedure, the natural glenoid surfaceof the scapula is restructured or otherwise replaced with a glenoidcomponent that provides a bearing surface for the head portion of thehumeral component.

With the average age of patients requiring shoulder arthroplastydecreasing, orthopaedic implant manufacturers are developing“bone-sparing” implants for the initial treatment of degenerativearthritis. While bone-sparing implants for the treatment of hip and kneearthroplasty are becoming quite common, bone-sparing shoulderarthroplasty techniques and prostheses are also being developed.

Shoulder surface replacement prostheses are being developed to replacethe articulating surface of the proximal humerus with a minimal boneresection and minimal disruption of the metaphysis and the diaphysis.Current designs use a semi-spherical articular dome with a small stemfor rotational stability. The under surface of the articular head isalso semi-spherical and meets with a spherically machined humeral head.

Typically, however, arthritis of the gleno-humeral joint causesflattening of the humeral head with a large medial osteophyte. The flathumeral head can cause voids in the bone under the prosthesis resultingin limited contact between the prosthesis and the resected bone and maylimit the load transfer capability between the prosthesis and thehumerus.

Referring now to FIG. 2, a healthy long bone or, in the form of, forexample, a humerus 1 is shown. The humerus 1 includes a head 2 on theproximal end of the humerus 1. The head 2 of a healthy humerus has aarcuate outer periphery. The arcuate outer periphery is generallyhemispherical and meets with a concave glenoid cavity 3.

Referring now to FIG. 3, a diseased humerus 4 is shown. The diseasedhumerus 4 includes a head 5. The head 5 is flattened as shown in FIG. 3.The humerus 4 also has developed a large medial osteophyte 7.

Referring now to FIG. 4, a prior art prosthesis 8 is shown in positionon the head 5 of diseased humerus 4. The head 5 includes a flattenedhumeral head area or bony defect 9, which leads to a void 6 between theprosthesis 8 and the bony defect 9.

When preparing a humeral head for a bone sparing or conservativeshoulder arthroplasty, the semi-spherical humeral head is prepared by,for example, a grater type hollow hemispherical grater-type reamer. Suchreamers are available from, for example, Othy, Inc., 460 West 350 North,Warsaw, Ind. 46580.

Additional steps to prepare the humeral head to receive a conservativeor bone sparing humeral prosthesis may be required. For example, thebone sparing or conservative humeral prosthesis may include a stem foranchoring the prosthesis into the humerus.

The humeral head needs to be prepared to receive the stem. Typically, adrill and/or a reamer may be required to prepare the prosthesis toreceive the stem. Such drills and reamers add time to the surgicalprocedure as well as represent a problem with the reamer having anorientation off center or skewed with respect to the hemisphericalportion of the prepared humerus.

Current resurfacing instrumentation, therefore, addresses bonepreparation techniques separately or sequentially. This type ofprocedure increases time, cost and mistakes. Operating room time isincreased because the surgeon and the operating room personnel arehandling more instrumentation. Cost is increased because moreinstruments need to be manufactured and processed. More mistakes can bemade because more instruments are handled and consequently the greateris the chance of dropping or making the wrong instrument selection.

SUMMARY

According to the present disclosure, a humeral head cutting tool isprovided that performs several precise cutting functions simultaneously.The cutting tool includes a concave cutting area which prepares a convexhead portion for the humeral prosthesis. The cutting tool also includesa tapered cylindrical reamer, which extends from the concave portion ofthe reamer to provide for an opening to receive the stem of theconservative or bone sparing prosthetic implant for the humerus.

The present disclosure provides for a long bone head cutting tool thatprepares the head of the long bone for receiving a trial in oneoperation that provides multiple cutting functions simultaneously.

According to one embodiment of the present disclosure, there is providedan instrument for use in performing arthroplasty. The instrumentincludes a first portion adapted to prepare a convex surface on the headof the long bone. The instrument also includes a second portion adaptedto prepare an elongated cavity or a third portion adapted to prepare acentral support surface on the head of the long bone, or both the secondand third portions. The third portion and the second portion areoperably associated with the first portion.

According to another embodiment of the present disclosure, there isprovided a reamer for use in performing arthroplasty. The reamerincludes a generally arcuate member having an inner concave surface andan outer convex surface adapted to prepare a convex surface on a bone.The arcuate member has an axis of rotation of the member. The reameralso includes a central member operably associated with the arcuatemember. The central member is adapted for preparing a support surface.The central member has an axis of rotation of the central member. Thereamer further includes a generally cylindrical member operablyassociated with the planar member or the arcuate plate, or both. Thecylindrical member is adapted for preparing a generally cylindricalsurface. The cylindrical member defines an axis of rotation of thecylindrical member.

According to a further embodiment of the present disclosure, there isprovided a cutting tool assembly for use in performing arthroplasty. Thecutting tool assembly includes a reamer. The reamer has a first portionadapted to prepare a convex surface, a second portion adapted to preparean elongated cavity and a third portion adapted to prepare a centralsurface. The first portion, the second portion and the third portion areoperably associated with each other. The cutting tool also includes adriver releasably securable to the reamer. The driver is adapted to beattachable to a power tool to rotate the reamer.

According to another embodiment of the present disclosure there isprovided a method from performing arthroplasty on the head of a longbone. The method includes the steps of providing a reamer having a firstcutting surface to prepare a convex support surface on the head of thelong bone and having a second cutting surface to prepare a cavity in thehead of the long bone, providing a prosthesis to resurface a portion ofthe head of the long bone, the prosthesis having a concave supportsurface and a stem, preparing the head of the long bone with the reamerto simultaneously prepare the convex support surface on the head of thelong bone and the cavity in the head of the long bone and implanting theprosthesis in the head of the long bone.

The technical advantage of the present disclosure includes the abilityto reduce the time to perform a shoulder arthroplasty. For example,according to one aspect of the present disclosure, a cutting tool isprovided that prepares the head of a long bone for receiving a trial inone operation by performing multiple cutting functions simultaneously.The cutting tool may, for example, provide the forming or cutting of theconvex humeral head as well as preparing the tapered opening to receivethe stem. Both the humeral head contour and the trial opening are thusprepared simultaneously with one instrument. Thus, separate taperedreamers and hollow hemispherical grater-type reamers are not required.Thus, the present disclosure provides for reduced time in the operatingroom by reducing the amount of instrumentation that the surgeon andstaff will need to handle during the operation.

Another advantage of the present disclosure includes reducing the costassociated with the instruments for an operation. For example, accordingto another aspect of the present disclosure, a long bone head shaperprepares the long bone head for trial seating in one operation byperforming multiple cutting functions simultaneously. The cutting toolmay include a concave grater-type reamer and a tapered cylindricalreamer all built into one cutting tool. This combination tool replacestwo separate tools, and therefore reduces cost. Thus, the presentdisclosure provides for cost reduction of instrument sets.

Another technical advantage of the present disclosure includes thereduction of surgical errors. For example, according to one aspect ofthe present disclosure, a cutting tool is provided that prepares thehead of a long bone for trial seating in one operation by performingmultiple cutting functions simultaneously. The tool may be in the formof, for example, a hollow hemispherical grater-type reamer with acentrally located tapered cylindrical reamer. The hemispherical portionprovides for a hemispherical head on the long bone and the taperedcylindrical portion provides for receiving the stem of the prosthesis.Since mistakes can be made because the more instruments the surgeonshandle the greater chance of dropping and damaging the instruments ormaking the wrong instrument selection can occur. Thus, the presentdisclosure provides for reductions in the likelihood of surgicalmistakes.

Another technical advantage of the present disclosure includes theability to optimize the accuracy of the surfaces prepared for aconservative or bone conserving long bone head implant. For example,according to one aspect of the present disclosure, a long bone headcutting tool is provided that prepares the head of the long bone fortrial or prosthesis seating in one operation by performing multiplecutting functions simultaneously. Since both the hemispherical head andthe stem are prepared with the same tool simultaneously, theconcentricity and alignment of the surfaces are optimized. Thus, thepresent disclosure provides for improved quality of the surfacesprepared for a prosthesis.

Other technical advantages of the present disclosure will be readilyapparent to one skilled in the art from the following figures,descriptions and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following descriptiontaken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a reamer according to the presentdisclosure that may be used to prepare the humerus for a surfacereplacement prosthesis for use on a diseased humerus;

FIG. 1A is another perspective view of the reamer of FIG. 1;

FIG. 1B is partial plan view of the reamer of FIG. 1 showing theopenings in the body in greater detail;

FIG. 1C is a partial bottom view of the reamer of FIG. 1 showing theplanar cutting surface in greater detail;

FIG. 1D is a partial plan view of the reamer of FIG. 1C along the line1D-1D in the direction of the arrows;

FIG. 1E is a partial plan view of the reamer of FIG. 1C along the line1E-1E in the direction of the arrows;

FIG. 1F is a partial plan view of the reamer of FIG. 1 showing thetapered cylindrical cutting surface in greater detail;

FIG. 1G is a partial plan view partially in cross section of anotherembodiment of the reamer of the present disclosure;

FIG. 1H is a partial plan view partially in cross section of yet anotherembodiment of the reamer of the present disclosure;

FIG. 1J is a partial plan view partially in cross section of anotherembodiment of the reamer of the present disclosure;

FIG. 1K is a partial plan view partially in cross section of anotherembodiment of the reamer of the present disclosure;

FIG. 1L is a partial bottom view of yet another embodiment of the reamerof the present disclosure;

FIG. 1M is a partial bottom view of another embodiment of the reamer ofthe present disclosure;

FIG. 1N is a partial cross-sectional view of the reamer of FIG. 1M alongthe line 1N-1N in the direction of the arrows;

FIG. 1P is a plan view partially in cross section of another embodimentof the reamer of the present disclosure;

FIG. 1Q is a bottom view of the reamer of FIG. 1P;

FIG. 1R is a plan view partially in cross section of the arcuate cuttingportion of the reamer of FIG. 1P;

FIG. 1S is a bottom view of the arcuate cutting portion of FIG. 1P;

FIG. 1T is a plan view partially in cross section of the cylindrical andcentral cutting portion of the reamer portion of FIG. 1P;

FIG. 1U is a bottom view of the cylindrical and central cutting portionof FIG. 1P;

FIG. 1V is a plan view partially in cross section of a cutter removaltool for the reamer of FIG. 1P;

FIG. 1W is a top view of the cutter removal tool of FIG. 1V;

FIG. 2 is a plan of a healthy humerus;

FIG. 3 is a plan of a diseased humerus;

FIG. 4 is a plan view partially in cross section of a prior art humeralprosthesis;

FIG. 5 is a plan view of a resected humerus showing the resected portionin phantom;

FIG. 6 is a plan view partially in cross section of a resected humeruswith a cavity prepared with the reamer of the present disclosure;

FIG. 7 is an auxiliary view of resected humerus with the cavity of FIG.6 prepared with the reamer of the present disclosure;

FIG. 8 is a plan view of a reamer assembly according to anotherembodiment of the present disclosure including a reamer and a reamerdriver;

FIG. 9 is a perspective view of the reamer with a plan view of thereamer driver of FIG. 8 shown disassembled as well as a plan view of anassembly tool used to install the cutting reamer onto the reamer driver;

FIG. 10 is an exploded perspective view of the reamer of FIG. 1 and thereamer driver of FIG. 8 shown with an assembly tool used to attached thereamer to the reamer driver;

FIG. 11 is a perspective view of the reamer of FIG. 9 show in positionon a humerus;

FIG. 12 is a perspective view of a trial for use on a humeral cavityprepared by the reamer of the present disclosure;

FIG. 13 is a perspective view of an implant for use on a humeral cavityprepared by the reamer of the present disclosure;

FIG. 14 is another perspective view of the implant of FIG. 13 for use ona humeral cavity prepared by the reamer of the present disclosure;

FIG. 15 is a plan view of set of surgical instruments that may be usedin performing shoulder arthroplasty according to a further embodiment ofthe present disclosure;

FIG. 16 is a plan view of the assembly tool of FIG. 10;

FIG. 17 is a plan view partially in cross section of a gauge with anoffset handle for determining the appropriate spacer of a surfacereplacement prosthesis for use on a diseased humerus prepared with thereamer of the present disclosure;

FIG. 18 is a plan view partially in cross section of a surfacereplacement prosthesis with a screwed-on spacer for use on the preparedhumerus prepared by the reamer of the present disclosure;

FIG. 19 is a plan view partially in cross section of another embodimentof a surface replacement prosthesis with a tapered fit spacer for use onthe prepared humerus prepared by the reamer of the present disclosure;

FIG. 20 is a plan view partially in cross section of another embodimentof a surface replacement prosthesis with a bolted-on spacer for use onthe prepared humerus prepared by the reamer of the present disclosure;

FIG. 21 is a plan view partially in cross section of another embodimentof a surface replacement prosthesis with a bolted-on spacer and stem foruse on the prepared humerus prepared by the reamer of the presentdisclosure;

FIG. 22 is a plan view partially in cross section of another embodimentof a surface replacement prosthesis with a screwed-on spacer with aportion of the prosthesis having porous coating for use on the preparedhumerus prepared by the reamer of the present disclosure;

FIG. 23 is a plan view partially in cross section of another embodimentof a surface replacement prosthesis with a three piece cup, spacer andstem assembly with porous coating for use on the prepared humerusprepared by the reamer of the present disclosure;

FIG. 24 is an exploded plan view partially in cross section of anotherembodiment of a surface replacement prosthesis with a three piece cup,plug and stem assembly for use on the prepared humerus prepared by thereamer of the present disclosure;

FIG. 25 is an exploded plan view partially in cross section of anotherembodiment of a surface replacement prosthesis kit with a three-piececonstruction including a cup, a set of two spacers and a stem for use onthe prepared humerus prepared by the reamer of the present disclosure;

FIG. 26 is a plan view of a kit including a plurality of cups, liners,stems, and spacers for use in performing shoulder arthroplasty accordingto a further embodiment of the present disclosure;

FIG. 27 is a process flow chart for a method of performing shoulderarthroplasty according to another embodiment of the present disclosure;and

FIG. 28 is a perspective view of a reamer installed in a reamer assemblytool shown in position on a femur according to another embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Embodiments of the present invention and the advantages thereof are bestunderstood by referring to the following descriptions and drawings,wherein like numerals are used for like and corresponding parts of thedrawings.

Referring now to FIG. 1, an instrument 10 is shown according to thepresent invention. The instrument 10 is used for performing arthroplastyon a long bone. The instrument 10 includes a first portion 11 adapted toprepare a convex surface on a head of a long bone. The instrument 10further includes a second portion 13 or a third portion 14. Theinstrument 10 may include both the second portion 13 and the thirdportion 14. The second portion 13 is adapted to prepare a cavity in theform of, for example, a trial hole 62 (see FIGS. 6 and 7) on the head 5of a long bone 4. The third portion 14 is adapted to prepare a planarsurface 56 on the head 5 of a long bone 4 (see FIGS. 6 and 7). As shownin FIGS. 1 and 1A, the first portion 11 comprises an arcuate disc-shapedbody for forming a generally hemispherical contour 64 on the long bone 4(see FIGS. 6 and 7).

Continuing to refer to FIGS. 1 and 1A, the instrument 10 may furtherinclude a fourth portion 16 extending from the first portion 11 in adirection opposed to the second portion 13. The fourth portion 16 isused for transferring torque to the instrument 10.

As shown in FIGS. 1 and 1A, the instrument 10 may be in the form of areamer. The reamer may be used to perform arthroplasty on, for example,a head 4 of a humerus 3 (see FIGS. 6 and 7).

Referring again to FIGS. 1 and 1A, the reamer 10 may include the arcuatedisc-shaped body or plate 15. The plate 15 may include the concavesurface 12 and an outer convex surface 17. The plate 15 is adapted toprepare the convex surface 64 on the head 5 of the bone 4 (see FIGS. 6and 7). The first portion 11 defines a first portion axis of rotation18.

The third portion or planar member 14 is operably associated with thefirst portion 11. The portion 14 is adapted to prepare the planarportion or resected surface 56 of the head 4 of the bone 5 (see FIGS. 6and 7). The planar member 14 defines an axis of rotation 19 of theplanar portion 14.

The instrument 10 may also include the second portion 13 or cylindricalmember which is associated with the planar member or the arcuate plate11. The cylindrical member 13 is adapted to prepare the trial stem hole62 of the head 5 of the bone 4 (see FIGS. 6 and 7). The cylindricalmember 13 defines an axis of rotation 20 thereof.

Referring now to FIGS. 1 and 1A, the first portion 11 may be in the formof a hollow hemisphere defined by an inner radius RI extending fromorigin 21 defining concave surface 12 and an outer radius RO originatingfrom origin 21 defining the outer convex surface 17. The distancebetween the concave surface 12 and the convex surface 17 may be definedby thickness T. The instrument 10 may include a concave surface cuttingfeature 22. The concave feature cutting feature may be any type of acutting tool and may include, for example, a plurality of blades (notshown) or other types of cutting edges. For example, and as shown inFIGS. 1 and 1A, the concave surface 12 may include a plurality of spacedapart openings 23. The cutting feature 22 may be in the form of cuttingsurfaces formed on the edge 24 of the openings 23 formed in the concavesurface 12.

Referring now to FIG. 1B, the cutting feature 22 and the form of edge 24on the openings 23 are shown in greater detail.

Referring again to FIG. 1, the first portion 11 may also include aplurality of circumferential saw teeth 25 extending from the circularperiphery 26 of the first portion 11. The teeth 25 serve to provide aproper seat for the prosthesis.

The instrument 10 including the first portion 11, second portion 13,third portion 14 and fourth portion 16, may be made of any suitabledurable material and may, for example, be made of a durable plastic, aceramic or a metal that is compatible with the human anatomy and whichmay be sterilized by a commercially available method. If made of ametal, the instrument 10 may be made of, for example, a titanium alloy,a cobalt chromium alloy, or a stainless steel alloy.

The first portion 11, if made of a metal, may be either formed, cast ormachined from a solid.

Referring again to FIGS. 1 and 1A, the third portion or planar member 14may, for example, be generally washer shaped.

Referring now to FIGS. 1C, 1D and 1E, the planar member 14 is shown ingreater detail. The planar member 14 may, for example, be generallywasher shaped having a diameter D and a thickness TP. The planar member14 may include a plurality of spaced apart blades 27.

Referring to FIG. 1E, the blades 27 may extend from planar member body28 at an angle, for example, of .alpha.. .alpha. may be, for example, 15to 55 degrees.

As shown in FIG. 1C, the plurality of blades 27 may be equally spaced.While there may be a solitary blade 27, a plurality of blades would eventhe cutting forces with a reasonable quantity of, for example, 3, 4, 5or 6 blades being suggested. Five blades are shown in the planar member14 of the instrument 10. The planar member 14 may include a centralopening 30 to provide for a central cannulation or to receive the secondportion 13.

The planar portion 14 may be manufactured by any suitable technique andmay, for example, be made of a stamping, a casting or machined fromsolid stock.

Referring now FIG. 1F, the tapered cylindrical member 13 is shown ingreater detail. The tapered cylindrical member may include a pluralityof lands or flutes 31. The lands 31 may includes a cutting edge 32. Thecutting edges 32 may be equally spaced around the periphery of thecylindrical member 13.

The number of lands 31 may be any suitable number and may be, forexample, 2, 3, 4, 5 or 6. The instrument 10 of the present inventionshows 4 spaced apart lands. Separating each particular land 31 is arelief 33. The tapered cylindrical reamer may include a tapered cuttingedge 34 defined by an included angle .beta. The cylindrical member 13may include a central hole or cannulation 35. The hole or cannulation 35may be used to assist in directing the instrument 10. The cylindricalmember 13 may be defined by a diameter CD and a length CL.

The cylindrical reamer 13 may be made by any suitable technique and may,for example, be machined from solid stock or extruded. The cylindricalreamer 13 may have a tapered shape defined by angle .theta.

Referring again to FIGS. 1 and 1A, the shank 16 extends in a directionopposed to the cylindrical member 13. The shank 16 serves to provide adriving mechanism to rotate the instrument. The shank 10 may begenerally cylindrical defined by a diameter DS and a length LS. Theshank 16 may have a shank centerline 37, which is generally coincidentwith the cylindrical member's centerline 20. To assist in the quickremoval of the instrument 10, the shank 37 may include a removal feature38 in the form of, for example, a bayonet mounting as shown in FIG. 1A.

Referring now to FIGS. 1G through 1N, the first portion 11, the secondportion 13, the third portion 14, and the fourth portion 16 of theinstrument 10 may all be integral to each other or be made of separatecomponents connected to each other. Any suitable method may be utilizedto connect the portions 11, 13, 14 and 16 if they are separablecomponents.

Referring now FIGS. 1G, 1H, 1J and 1K, the fourth portion, which isgenerally cylindrical, and the third portion which is generallycylindrical and which have generally the same centerline can veryreasonably be integral with each other. For example, instrument 10G ofFIG. 1G shows the fourth portion 16G being integral with the secondportion 13G. Similarly, instrument 10H of FIG. 1H shows the fourthportion 16H being integral with the second portion 13H. Furtherreferring to FIG. 1K, the instrument 10K shows the fourth portion 16Kbeing integral with the second portion 13K.

Referring now to FIG. 1J, the instrument 10J is shown with the fourthportion 16J and the second portion 13J being separable components. Asshown in FIG. 1J, the fourth portion 16J and the second portion 13J areinterferencely fit. It should be appreciated that the second portion 13Jand fourth portion 16J may be welded, taper locked or threaded to eachother, for example.

Referring now to FIGS. 1K, 1L, 1M and 1N, the third portion 14 may besecured to the first portion 11 in any suitable fashion. For example,referring to FIG. 1K, the third portion 14K of instrument 10K may besecured to the first portion 11K by means of welding between the outerperiphery of the third portion 14K and the first portion 11K.

Further referring now to the instrument 10L of FIG. 1L, the thirdportion 14L may be welded to the first portion 11L by a plurality ofwelds 39L located in a spaced-about position on the third portion 14L.

Referring now to instrument 10M of FIGS. 1M and 1N, the third portion14M may be connected to the first portion 11M by means of a pluralityspaced-apart fasteners in the form of, for example, threaded fasteners39M. The fasteners 39M will secure the third portion 14M to the firstportion 11M.

Referring now to FIGS. 1G, 1H, 1J, and 1K, it should be appreciated thatthe first portion 11 may be secured to the second portion 13 and thefourth portion 16 in any suitable manner. For example, referring to FIG.1G, the second portion 13G and the fourth portion 16G may be integraland include a circumferential recess 40G into which the first portion11G, that includes third portion 14G, may be snap-fitted.

Referring now to FIG. 1H, the second portion 13H may be integral withthe fourth portion 16H and the portions 13H and 16H may include ashoulder 40H there between upon which the first portion 11H may besecured. It should be appreciated that the first portion 11H may bewelded or interferencially fit to the second portion 13H.

Referring now to FIGS. 1J and 1K, the first portions 11J and 11K may bewelded to the fourth portions 16J and 16K, respectively.

Referring now to FIGS. 1P-U, another embodiment of the present inventionis shown as instrument 10P. The instrument 10P includes a first portion11P, a second portion 13P and a third portion 14P. The first portion 11Pand the second portion 13P may be similar to the first portion 11 andthe second portion 13 of the instrument 10 of FIG. 1. The instrument 10Pmay also include a fourth portion 16P similar to fourth portion 16 ofthe instrument 10 of FIG. 1.

The third portion 14P may be a separate component from the first portion11P and the second portion 13P, or as shown in FIG. 1T, the thirdcomponent 14P may be integral with the second portion 13P and the fourthportion 16P.

Referring now to FIG. 1Q the third portion 14P includes a blade 27Pextending outwardly from the second portion 13P. The third portion 14Pmay have a solitary blade 27P, or as shown in FIG. 1Q the blade 27P mayhave four equally spaced apart blades 27P.

The instrument 10P also includes the second portion or cylindricalmember 13P that is integral with the third member 14P and the fourthmember 16P. The cylindrical member 13P is adapted to prepare the trialstem hole 62A of the head 4 of the bone 3 (see FIGS. 6 and 7). Thecylindrical member 13P defines an axis of rotation thereof.

Referring again to FIGS. 1P and 1Q, the first portion 11P may be in theform of a hollow hemisphere defining concave surface 12P and an outerconvex surface 17P. The instrument 10P includes a concave surfacecutting feature 22P in the form of cutting surfaces formed on edge 24Pof openings 23P formed in the concave surface 12P (see FIG. 1Q). Thefirst portion 11P may include through slots 29P to assist bone chipremoval and sterilizing.

Referring again to FIG. 1P, the first portion 11P may also include aplurality of circumferential saw teeth 25P extending from the circularperiphery 26P of the first portion 11P.

Referring now to FIGS. 1R and 1S the first portion 11P is shown as aseparate component. As a separate component the first portion 11P can beeasily sterilized.

Referring now to FIGS. 1T and 1U the second portion 13P, the thirdportion 14P, and the fourth portion 16P are shown as an integral reamercomponent 33P. As a separate component the integral reamer component 33Pcan be more easily sterilized.

Referring again to FIG. 1P the first portion 11P can be assembled ontothe integral reamer component 33P with shaft 37P of the integral reamercomponent 33P fitting into the opening 35P of the first portion 11P.Threads 94P on the driver 71P (shown in phantom) and the collar 34P areused to move the collar of driver 71 P toward first portion 11P,trapping the first portion 11P between the collar and a convex portionof the third portion 14P.

The instrument 10P including the first portion 11P, second portion 13P,third portion 14P and fourth portion 16P, may be made of any suitabledurable material and may, for example, be made of a durable plastic, aceramic or a metal that is compatible with the human anatomy and whichmay be sterilized by a commercially available method. If made of ametal, the instrument 10P may be made of, for example, a titanium alloy,a cobalt chromium alloy, or a stainless steel alloy.

Referring now to FIGS. 1V and 1W, a cutting tool assembly wrench 82P isshown. The wrench 82P performs the same function as the wrench 82 ofFIG. 16, namely it secures the tool 10P to the driver 71P. The wrench82P includes a cylindrical body 83P and a cylindrical shaft 84Pextending from a first end 85P of the body 83P.

The wrench 82P further includes an adapter block 86P slidably fitted tothe shaft 84P and the block 86P may move to position 89P (shown inphantom). A guide pin 91P is fixedly secured to shaft 84P and is used toalign the wrench 82P to the tool 10P. Drive tangs 88P located on theblock 86P engage with slots 87P (see FIG. Q) on the circular periphery26P of the first portion 11P of tool 10P. The wrench 82P is rotated withrespect to the tool 10P and a removal feature in the form of a bayonetmounting 38P on the shaft 37P of the tool 10P engages with the driver71P.

Referring now to FIGS. 5, 6 and 7, a long bone in the form of a humerus4 is shown in varying stages of preparation for receiving a prosthesisutilizing the gauge of the present invention as well as the surgicalmethod of the present invention. Referring to FIG. 5, the humerus 4 isshown with a portion of the flattened head 5 resected. The head 5 isresected along resection line 54 providing a resected surface 56. Thesurface 56 may be resected by any suitable method, for example, areamer, a mill end cutter, a saw, or an osteotome. The location of theresection line 54 may be determined by utilizing the gauge 410 of FIG.17. The indicia 434 on the gauge 410 of FIG. 17 may be utilized todetermine the position of the resection line 54 and the proper depth ofthe surface 56.

Referring now to FIGS. 6 and 7, the long bone in the form of humerus 4is shown with the head 5 being prepared for a prosthesis used inconjunction with the instrument and surgical procedure of the presentinvention. Any suitable tool may be utilized to form the mounting holeor counter bore 62. For example, the mounting hole or counter bore 62may be machined into the humerus 4 by use of a reamer. The counter bore62 may be positioned a depth CDH from the resection line 54. Thedimension CDH may be established utilizing the gauge 10 of FIG. 1. Thegauge 410 of FIG. 17 may establish the proper prosthesis for a givenbone contour and the dimension CDH may correspond to that recommendedfor that particular prosthesis.

The preparation of the head 5 of the humerus 4 may further include anarcuate support surface 64 formed adjacent the head 5. The arcuatesurface 64 preferably conforms to that of the prosthesis and isgenerally arcuate and may be generally hemispherical. The arcuatesurface 64 may be machined into the humerus 4 in any suitable fashionand may be machined by the reamer of the present invention. For example,the arcuate surface 64 may be applied by a grater-type reamer.

The position of the arcuate surface 64 may be determined by, forexample, a depth AH at a diameter AD. The dimensions AD and AH may bedetermined with the assistance of the gauge 410 of FIG. 17. For example,the gauge 10 may be utilized to determine the proper prosthesis and thedimensions AH and AD may be determined upon that particular prosthesis.

The gauge 410 of FIG. 17, may be used to select the proper amount ofresection to the humeral head and, correspondingly, the properprosthesis to be used for that particular resection. It should beappreciated that due to the variations in the size of the patient andhis or her respective humerus, a wide variety of prostheses may berequired to accommodate the variations in a patient's humerus. Not onlymay the selection of a proper prosthesis be governed by the properradius of the articulating surface, variations in the progress of theosteoarthritis may result in the flattening of the head of the humerusbeing in various stages of progression.

Due to the changes in the progression of the disease and the resultingshape of the humeral head, the resection plane may vary from beingsomewhat shallow to being much deeper into the humerus. Therefore, evenfor a given size of the articulating surface of the prepared naturalhumerus, the position of the resection, including the planar part of theresection of the humerus, may vary.

These various needs may be accomplished by providing a wide variety ofsizes and configurations of the prosthesis. The availability of a widevariety of sizes and configurations of prostheses may be quite costlyboth in manufacturing lot sizes as well as in inventory. The applicantshave discovered that the prosthesis may be made with more than onecomponent.

Referring now to FIG. 8, and according to another embodiment of thepresent invention, a cutting tool assembly 70 is shown. The cutting toolassembly 70 is utilized to perform arthroplasty, for example, aconservative or bone sparing arthroplasty to the head of a long bone.The cutting tool assembly 70 includes an instrument or cutting tool inthe form of reamer 10. The reamer 10 includes first portion 11 adaptedto prepare a convex surface, third portion 14 adapted to prepare aplanar surface, and second portion 13 adapted to prepare an elongatedcavity.

The cutting tool assembly 70 further includes a driver or tool holder71. The driver 71 is releasably securable to the reamer 10. For example,the driver 71 includes a tool-releasing adapter 72, which is used torelease the reamer 10 from the driver 71. Any standard available toolreleasing adapter 72 may be utilized. As shown in FIG. 8, the driver 71is adapted to be attachable to a power tool 73 to rotate the reamer 10.The power tool 73 may, for example, be a magnetic rotational tool, anelectric rotational tool, or a hydraulic rotational tool, allcommercially available. A driver adapter 74 may be utilized to attachthe driver 71 to the power tool 73.

Referring to FIG. 11, the cutting tool assembly 70 is shown in positionagainst humeral head 5 of humerus 4.

Referring now to FIGS. 9 and 10, the tool assembly kit 80 is shown.Referring to FIG. 9, the cutting tool assembly kit 80 includes thereamer or cutting tool 10 and the driver 71. The kit 80 further includesa cutting tool assembly wrench 82.

Referring now to FIGS. 10 and 16, the cutting tool assembly wrench 82includes a cylindrical body 83 and a first handle 84 extending from afirst end 85 of the body 83. The wrench 82 further includes a fork 86extending from a second end 87 of the body 83.

The fork 86 includes a drive pin 88 for cooperation with the hole 35 ofthe second portion 13 of reamer 10 to guide the assembly wrench 82 intothe reamer 10. The fork 86 further includes a pair of spaced-apart driveor engagement pins 90 which mate with openings (not shown) on thecutting tool or reamer 10.

By rotating the handle 84 of the wrench 82 in the direction of arrow 92while pushing upward in a direction 93 and compressing spring 94 of thedriver 71, the cutting tool pin may be released.

Referring now to FIG. 12 a trial 164 for use with the prosthesis of thepresent invention is shown. The trial 164 is utilized during shoulderarthroplasty to verify the proper selection of the prosthetic member byimplanting the trial 164 into the humeral head and performing trialreductions on the arm to verify the selection of the particularly sizedtrial and corresponding prosthesis. The trial 164 is removed andreplaced with the corresponding prosthesis. The trial 164 may be reusedafter sterilization. The trial is made of any suitable durable materialand may, for example, be made of a durable plastic that may besterilized by standard methods such as used in an autoclave.

The trial 164 mimics the size and shape of the prosthesis. The trial 164therefore includes an articulating surface 165 and an opposed supportsurface 166. The trial 164 further includes a stem 167 extendingoutwarding from the support surface 166. As shown in FIG. 12, the trial164 may also include a plurality of spaced apart openings 169 to assistin the removal of the trial 164.

Referring now to FIGS. 13 and 14, an integral or one-piece humeralimplant 200 is shown for use with the instrument of the presentinvention. The implant 200 may be made of any suitable durable materialand may, for example, be made of a metal that is compatible with thehuman body. For example, the implant 200 may be made of a cobaltchromium alloy, a titanium alloy, or a stainless steel alloy.

The humeral implant 200 may include a body 220 having a arcuatearticulating surface 222 and an opposed support surface 226. The supportsurface 226 may include an arcuate support surface 234 and a planarsupport surface 236. The humeral implant 200 may further include a stem240 extending from the support surface 226 of the body 220. The stem 240may be generally cylindrical and may, for example, be tapered.

For example and as shown in FIG. 13, the stem 240 may include a locatingstem portion 272 extending from the support surface 226 and a securingstem portion 274 extending from the location stem portion 272.

The arcuate articulating surface 222 and the arcuate support surface 234may both be hemispherical. For example, the articulating surface 222 maybe defined by a radius HR extending from origin 276. Similarly, thearcuate support surface 234 may be defined by radius HS extending fromthe origin 276. The planar portion 236 of the support surface 226 may begenerally disc-shaped and may be defined by diameter PD.

The locating stem portion 272 may be generally conifrustrical and may bedefined by diameter LDS and length LSH, as well as, by included angle.alpha..alpha.. Similarly, the securing stem portion 274 may begenerally conifrustrical and be defined by diameter SSD and length SSHas well as by angle .gamma. The securing stem portion 274 may include aplurality of spaced-apart flutes 280 separated by recesses 282. A tip284 may extend outwardly from the securing stem portion 274 at an angle.alpha..alpha..alpha.

Referring now to FIG. 15, a kit 370 for use when performing anarthroplasty to implant the prosthesis of the present invention. The kit370 includes the guide pin 360, a guide pin alignment tool 371 forassisting in aligning the guide pin and positioning it into the humerus.The instrument kit 370 also includes the cutting tool assembly 372 forpreparing the humeral head. The instrument kit 370 further includes thecutting tool assembly wrench 373 for assembling and disassembling thecutting tool from the cutting tool assembly 372. The instrument kit 370also includes forceps 374 for securely gripping items. The instrumentkit 370 also includes a humeral head impactor 375, which is used with asurgical mallet 376 to drive the implant into its final seat.

Referring now to FIG. 17, a gauge 410 for use in measuring theflattening of the natural humerus is shown. The gauge 410 is used toassist in selecting the proper sized implant. The gauge 410 is designedto assist in the ease of viewing the position of the gauge with respectto the bone contour 12.

As shown in FIG. 17, the gauge 410 includes a body 414 having acylindrical portion 422. The body 414 further includes a hollowhemispherical portion 424, which has an inner periphery 438, whichminimizes the locating surface of the implant. The cylindrical portion422 includes a longitudinal cylindrical opening 428 as well as anindicia opening 436 for viewing indicia 434. The hemispherical portion424 includes a viewing window 444 to view the head 5 in assisting theproper positioning of the gauge 410.

As shown in FIG. 17, the gauge 410 includes a separate handle 454separate from the cylindrical body 422. The handle 454 is utilized forholding the gauge 410 in position with respect to the head 5. It can beseen that the handle 454 is preferably opposed to the viewing window 444so that the head 5 may be clearly viewed through the viewing window 444while the gauge 410 is being held by the handle 454.

Referring now to FIG. 18, an example of a multi-piece prosthesis isshown as prosthesis 510. Prosthesis 510 of FIG. 18 is similar to theprosthesis 200 of FIG. 13 except that the prosthesis 510 is made of twocomponents rather than the solitary component of the prosthesis 200 ofFIG. 13.

As shown in FIG. 18, the prosthesis 510 includes in addition to a body520, a spacer 550. The spacer 550 provides for a variety of locations ofthe planar portion 536 of support surface 526. Thus, by utilizing theprosthesis 510, a common body 520 may be used with a variety of spacers550 having different thicknesses T1. Thus, for any prosthesis 510 aplurality of planar dimensions PD may be provided by merely changing thespacer 550 to either a thinner or a thicker spacer.

As shown in FIG. 18, the prosthesis 510 includes the body 520. The body520 includes an articulating surface 522 extending in a second direction532 as well as a stem 540 extending in a first direction 530 opposed tothe second direction 532.

As shown in FIG. 18, the body 520 includes a body planar surface 552 towhich the spacer 550 is placed. The spacer 550 defines the planarportion 536 of the support surface 526 and works in conjunction witharcuate surface 534 of the body 520 to support the prosthesis 510against the humerus wall.

As shown in FIG. 18, the spacer 550 preferably has a pair of spacedapart parallel faces defined with the thickness T1. The spacer 550 has acentral opening 554 to permit the spacer 550 to be positioned in placeagainst the body planar surface with the stem 540 passing through theopening 554.

Preferably, and as shown in FIG. 18, the spacer 550 is secured to thebody 520 by, for example, a connector 556. The connector 556 may, asshown in FIG. 5, be in the form of a threadable connection. For example,the connector 556 may include external threads 560 located on the distalportion of the stem 540. The external threads 560 on the stem 540cooperate with matching internal threads 562 on the spacer 550. Afeature (not shown) in the form of, for example, a recess on the planarportion 536 of the spacer 550 may be utilized to secure the spacer 550against the body 520. The body 520 and the spacer 550 may be made of asimilar material to that of the prosthesis 200. Thus, for example, thebody 520 and the spacer 550 may be made of a cobalt chromium alloy, atitanium alloy or a stainless steel alloy.

Referring now to FIG. 19, another embodiment of the present invention asprosthesis 610. Prosthesis 610 includes a body 620 similar to the body520 of the prosthesis 510 of FIG. 18 in that the body 620 includes stem640 similar to stem 540 of FIG. 18. The prosthesis 610 further includesa spacer 650 similar to the spacer 550 of the prosthesis 510 of FIG. 18.

The spacer 650 is secured to the body 620 by means of a connector 656.The connector 656 is different that the connector 556 of the prosthesis510 in that the connector 656 is in the form of a taper fit. The spacer650 includes a tapered opening 662 which engages with tapered stemportion 660 of the stem 640 of the prosthesis 610. The body 620 includesan articulating surface 622 and an opposed arcuate support surface 634.The spacer 650 includes a planar support surface 636 which together withthe arcuate support surface 634, form the support surface 626 forsupporting the prosthesis 610 within the humerus 12.

Referring now to FIG. 20, another embodiment of the present invention isshown as prosthesis 710. The prosthesis 710 of FIG. 20 is similar to theprosthesis 610 of FIG. 19, and includes a body 720 similar to the body620 of FIG. 19. The body 720 includes an articulating surface 722 and anopposed arcuate support surface 734. The body 720 in integral with astem 740 similar to the stem 640 of FIG. 19. The prosthesis 710 furtherincludes a spacer 750 similar to the spacer 650 of the prosthesis 610 ofFIG. 19.

The spacer 750 is secured to the body 720 of the prosthesis 710 by meansof a connector 756, which is different than the connector 656 of theprosthesis 610 of FIG. 19. The connector 756 is in the form of aplurality of socket head hex cap screws. The cap screws 756 are fittedinto recessed openings 766 in the spacer 750. The cap screws 756 aresecured to the body 720 by a plurality of threaded openings 768. Thespacer 750 provides planar support surface 736.

Referring now to FIG. 21, another embodiment of the present invention isshown as prosthesis 810. Prosthesis 810 is similar to the prosthesis200, 510, 610 and 710 in that the prosthesis 810 includes a body 820, aspacer 850, and a stem 840. The prosthesis 810 is different than theprosthesis 200, 510, 610 and 710 in that the spacer 850 and the stem 840are integral with each other. The body 820 of the prosthesis 810 thusdoes not include the stem 840 and is a separate part from the spacer 850and the stem 840.

As shown in FIG. 9, the body 820 has a generally hollow hemisphericalshape having a articulating surface 822 and an opposed arcuate supportsurface 834. The spacer 850 has a general disc shape with the stem 840having a generally cylindrical shape and extending outwardly from thecenter portion of the spacer 850.

The spacer 850 is secured to the body 820 by means of a connector 856.The connector 856 as shown in FIG. 21 is in the form of a threaded stemextending from the spacer 850 in a direction opposed to the stem 840.The connector 856 includes external threads 860, which mate withinternal threads 862 in the body 820. The spacer 850 forms planarsupport surface 836, which together with the arcuate support surface 834forms support surface 826 for supporting the prosthesis 810 against thehumerus 12.

Referring now to FIG. 22, another embodiment of the present invention isshown as prosthesis 910. Prosthesis 910 is similar to the prosthesis 810of FIG. 21. Prosthesis 910 includes a body 920 similar to the body 820of FIG. 21 and includes an articulating surface 922 and opposed arcuatesupport surface 934. The body 920 includes a stem 940 similar to thestem 840 of FIG. 21. The prosthesis 910 further includes a spacer 950similar to the spacer 850 of FIG. 21. The spacer 950 includes a planarsupport surface 936, which together with the arcuate support surface 934serves to form support surface 926 for supporting the prosthesis 910against the humerus 12. The prosthesis 910 further includes a connector956 similar to the connector 556 of the prosthesis 510 of FIG. 18.

Unlike the prosthesis 110, the prosthesis 910 includes a porous coating970 located on the planar support surface 936 and the arcuate supportsurface 934. The porous coating 970 serves to provide additional surfacefor promoting bony ingrowth into the prosthesis 910 for improvedfixation of the prosthesis 910 to the humerus 12. Any suitablecommercially available porous coating may be suitable for the coating970. For example, the coating may be in the form of POROCOAT®, a productof the assignee of the instant application. More information regardingthe coating may be available by referring to U.S. Pat. No. 3,855,638 toPilliar incorporated herein by reference in its entirety.

Referring now to FIG. 23, another embodiment of the present invention isshown as prosthesis 1010. Prosthesis 1010 is a three-part prosthesisincluding a body 1020 similar to the body 920 of the prosthesis 910 ofFIG. 22. The body 1020 includes a hemispherical outer articulatingsurface 1022 and a concave internal arcuate support surface 1034. Theprosthesis 1010 further includes a plug 1050, which serves the purposeof the spacer 950 of the prosthesis 910 of FIG. 22. The plug 1050includes a planar support surface 1036 and an opposed spherical outersurface 1072 which mates with the arcuate support surface 1034 of thebody 1020. The plug 1050 may be secured to the body 1020 by any suitablemethod. For example, as shown in FIG. 23, a first connector 1056 in theform of a taper connection is shown.

The first connector 1056 includes an exterior taper 1060 extending fromthe plug 1050, which mates with an internal taper 1062 in the body 1020.The prosthesis 1010 further includes a generally cylindrical taperedstem 1040, which is secured to the plug 1050 by a second connector 1074.

The stem 1040 may be secured to the plug 1050 by, for example, a secondconnector 1074. The second connector 1074 may have any suitableconfiguration and may, as shown in FIG. 23, be in the form of anexternal taper 1076 located on the stem 1040, which cooperates with aninternal taper 1078.

As shown in FIG. 23, the prosthesis 1010 may further include a coating1070 in the form of, for example, a porous coating, for example,POROCOAT® to encourage ingrowth to assist in the securement of theprosthesis 1010 to the humerus 12. The coating 1070 may be secured tothe stem 1040 as well as to the arcuate support surface 1034 as well asthe planar support surface 1036.

Referring now to FIG. 24, another embodiment of the present invention isshown as prosthesis 1110. Prosthesis 1110 is similar to prosthesis 1010of FIG. 23 and includes three components, namely a body 1120 similar tobody 1020 of the prosthesis 1010 of FIG. 23, a stem 1140 similar to thestem 1040 of the prosthesis 1010 of FIG. 23, and a plug 1150. The plug1150 is similar to the plug 1050 of the prosthesis 1010 of FIG. 23except that the plug 1150 and the stem 1140 are secured to the body 1120in a different fashion from that of the prosthesis 1010. While theprosthesis 1110 similar to the prosthesis 1010, in that it has itscomponents interconnected by means of tapered connections, the taperedconnections of the prosthesis 1110 are different from those of theprosthesis 1010 of FIG. 23.

For example, the prosthesis 1110 includes a first connector 1156 in theform of a tapered connection. The tapered connection 1156 includes anexternal taper 1160 formed on the stem 1140, which connects with aninternal taper 1162 formed on the body 1120.

The plug 1150 is secured to the stem 1140 by means of a second taperedconnection 1174. The second tapered connection 1174 includes an externaltaper 1176 formed on the stem 1140 which connects with an internal taper1178 formed on the plug 1150. The plug 1150 includes a support surface1136 which, together with arcuate surface 1134 of the body 1120 formsupport surface 1126 of the prosthesis 1110 for securing the prosthesis1110 to the humerus 12.

Referring now to FIG. 25, another embodiment of the present invention isshown as kit 1200. The kit 1200 includes a body 1220 similar to the body1020 of the prosthesis 1010 of FIG. 23. The body 1220 includes anarticulating surface 1222 and an opposed support surface 1234. The kit1200 further includes a first spacer in the form of a plug 1250. Thefirst spacer 1250 is similar to the first spacer or plug 1050 of theprosthesis 1010 of FIG. 23. The body 1220 and the first spacer 1250combine to form prosthetic member 1210. The prosthetic member 1210 mayfurther include an optional stem 1240 similar to the stem 1040 of FIG.23.

The kit 1210 in addition to the first spacer 1250 includes a secondspacer 1280. The second spacer 1280 may selectively be included orexcluded from the prosthetic member 1210 such that planar supportsurface 1236 may be located for example on the first spacer 1250 oralternatively on the second spacer 1280. The kit 1200 may optionallyfurther include a third spacer 1282 or additional spacers (not shown).

When the kit 1200 includes the body 1220, the first spacer 1250 and thesecond spacer 1280, the kit 1200 may be utilized by selectively pickingthe inclusion or non-inclusion of the second spacer 1280, therebyproviding for a variation in the location of the support surface 1236.

The kit 1200 serves to permit the use of a prosthesis with a variety oflocations for the support surface 1236. The ability to vary the locationof the support surface is important when dealing with diseased humerusin which the flattened head may vary from patient to patient, and thecorresponding required amount of resection may vary for a given geometryof the humerus.

The prosthetic of kit 1200 may be built by utilizing the body 1220 andthe plug 1250 as well as a combination of one or the other of the secondand third spacers 1280 or 1282, respectively, or by the use of bothspacers 1280 and 1282. Similarly, the prosthetic member 1210 may beperformed without the use of either the second spacer 1280 or the thirdspacer 1282.

Preferably and as shown in FIG. 25, the first spacer 1250 is secured tothe body 1220 by use of a first tapered connection 1256. The firsttapered connection 1256 as shown in FIG. 25, includes an external taper1260 formed on the first spacer 1250, which mates with an internal taper1262 formed on the body 1220.

The second spacer 1280 may be secured to the plug 1250 by the use of asecond tapered connection 1274. The second tapered connection 1274 mayinclude an external taper 1276 formed on the second spacer 1280 whichmates with an internal taper 1278 formed in the first spacer 1250.Similarly, the second spacer 1280 may be connected to the third spacer1282 by means of a third tapered connection 1284. Similarly, the thirdspacer 1282 may be connected to the stem 1240 by means of a fourthtapered connection 1286.

Preferably and as shown in FIG. 25, the second tapered connection 1274,the third tapered connection 1284 and the fourth tapered connection 1286are identical to each other so that the stem 1240 may be connected toany of the first spacer 1250, second spacer 1280 or third spacer 1282.

Referring now to FIG. 26, another embodiment of the present invention inthe form of kit 1300 is shown. Kit 1300 is similar to kit 1200 of FIG.25 but includes additional components so that patients with greatlyvarying humeral sizes as well as varying conditions of the flattening ofthe humeral head, may be accommodated within the kit 1300. For example,as shown in FIG. 26, the kit 1300 includes a plurality of cups, plugs,spacers and stems so that a wide variety of patient humeral conditionscan be accommodated.

As shown in FIG. 26, the kit 1300 includes a first cup 1320 having afirst size articulating surface 1322. The kit 1300 also includes asecond cup 1320A. The cup 1320A includes an articulating surface 1322Awhich is larger than the articulating surface 1322. The kit 1300 mayalso include a third cup 1320B, having an articulating surface 1322B,which is larger than the articulating surface 1322A of the cup 1320A.

So that the cups 1320, 1320A and 1320B may be utilized with commonspacers, plugs and stems, preferably and as shown in FIG. 26, the cup1320 has an internal arcuate surface 1334 which is the same size andshape as the articulating surface 1334A of the cup 1320A which is alsothe same size and shape as articulating inner surface 1334B of the cup1320B.

The kit 1300 further includes a first plug 1350 having a planar surface1336 and an opposed arcuate surface 1372. The arcuate surface 1372 ofthe first plug 1350 matingly fits against the arcuate surface 1334 ofthe first cup 1320. The kit 1300 further includes a second plug 1350A aswell as a third plug 1350B.

The first plug 1350, the second plug 1350A and the third plug 1350Bpreferably each have a respective arcuate periphery 1372, 1372A and1372B which all matingly fit with the arcuate surface 1334 of the cup1320. Thus, the first plug 1350, the second plug 1350A and the thirdplug 1350B may be selectively mated with the first cup 1320. The firstplug 1350, the second plug 1350A and the third plug 1350B each have arespective support surface 1336, 1336A and 1336B which provide forvarying amounts of resection of the humerus 12.

The kit 1300 further includes a first spacer 1380, a second spacer1380A, a third spacer 1380B and a fourth spacer 1380C. Each of thespacers 1380, 1380A, 1380B and 1380C have different thicknesses toaccommodate a different amount of resection of the humerus 12.

The kit 1300 may further include a plurality of stems, for example, afirst stem 1340, a second stem 1340A, and a third stem 1340B. Each ofthe stems 1340, 1340A and 1340B have a different length to accommodate adifferent size humerus. Preferably, and as shown in FIG. 26, for thecomponents of the kit 1300 to be able to be easily matched, thecomponents have external tapers 1360 which are all identical as well asinternal tapers 1362 which are all identical, so that any internal taper1362 may fit against an external taper 1360.

For example, as shown in FIG. 26, the cup 1320 may be combined with theplug 1350 to form a first prosthetic member 1310 and the second plug1350A may be combined with the second cup 1320A to form a secondprosthetic member 1311.

The kit 1300 may further include instruments 1358 to be used inconjunction with installing and removing the prosthesis.

Referring now to FIG. 27, a method for performing arthroplasty on thehead of a long bone is shown as method 1400. Method 1400 includes firststep 1402 of providing a reamer having a first cutting surface toprepare a convex support surface on the head of the long bone and havinga second cutting surface to prepare a cavity in the head of the longbone. The method 1400 includes a second step 1404 of providing aprosthesis to resurface a portion of the head of the long bone, theprosthesis having a concave support surface and a stem. The method 1402includes a third step 1406 of preparing the head of the long bone with areamer to simultaneously prepare the convex support surface on the headof the long bone and the cavity in the head of the long bone. The method1400 further includes a fourth step 1408 of implanting the prosthesis inthe head of the long bone.

Referring now to FIG. 28, and according to another embodiment of thepresent invention, a cutting tool assembly 1570 is shown. The cuttingtool assembly 1570 is similar to the cutting tool assembly 70 of FIG. 8except the cutting tool assembly 1570 is designed to be used on thefemoral head 1505 of femur 1504. The cutting tool assembly 1570 is shownin position against femoral head 1505 of femur 1504. The cutting toolassembly 1570 is utilized to perform arthroplasty, for example, aconservative or bone sparing arthroplasty to the head of the femur 1504.

The cutting tool assembly 1570 includes an instrument or cutting tool inthe form of a reamer 1510. The reamer 1510 includes a first portion 1511adapted to prepare a convex surface, a second portion 1513 adapted toprepare a planar surface, and a third portion 1514 adapted to prepare anelongated cavity. The reamer 1510 may also include a shank 1516 to beused to rotate the reamer 1510.

The cutting tool assembly 1570 further includes a driver or tool holder1571. The driver 1571 is releasably securable to the reamer 1510. Forexample, the driver 1571 includes a tool-releasing adapter 1572 that isused to release the reamer 1510 from the driver 1571. Any standardavailable tool-releasing adapter 1572 may be utilized. As shown in FIG.28, the driver 1571 is adapted to be attachable to a power tool 1573 torotate the reamer 1510. The power tool 1573 may, for example, be amagnetic rotational tool, an electric rotational tool, or a hydraulicrotational tool, all commercially available. A driver adapter 1574 maybe utilized to attach the driver 1571 to the power tool 1573.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions, andalterations can be made therein without departing from the spirit andscope of the present invention as defined by the appended claims.

What is claimed is:
 1. A reamer for use in performing arthroplasty, thereamer comprising: a first cutting structure having an inner concavesurface that defines a first cavity and terminates distally in agenerally circular leading edge, the inner concave surface including afirst cutting feature that is spaced apart from the leading edge; anelongate member extending from the inner concave surface through thefirst cavity and toward the leading edge, the elongate member includinga second cutting feature, the second cutting feature being located atleast partially within the first cavity; and a second cutting structuresecured to said elongate member and positioned within the first cavity,the second cutting structure extending outwardly from the elongatemember toward the inner concave surface and including a third cuttingfeature, wherein the first cutting feature comprises a plurality ofopenings defined in the first cutting structure that extend through theinner concave surface, each of the openings having a cutting edge. 2.The reamer of claim 1, wherein the first cutting structure has agenerally hemispherical shape.
 3. The reamer of claim 1, wherein theleading edge of the first cutting structure comprises a cutting edge. 4.The reamer of claim 3, wherein the leading edge includes a plurality ofcutting teeth.
 5. The reamer of claim 1, wherein the elongate member istapered.
 6. The reamer of claim 1, wherein the second cutting featurecomprises a plurality of flutes.
 7. The reamer of claim 1, wherein theelongate member is cannulated.
 8. The reamer of claim 1, wherein thesecond cutting structure comprises at least one cutting blade thatextends outwardly from the elongate member.
 9. The reamer of claim 8,wherein the second cutting structure comprises a plurality of cuttingblades that evenly spaced apart from each other around a circumferenceof the elongate member.
 10. The reamer of claim 8, wherein the pluralityof cutting blades are cantilevered from the elongate member.
 11. Thereamer of claim 8, wherein the second cutting structure is fixed to theelongate member, and wherein the elongate member is removably attachedto the first cutting structure.
 12. A reamer for use in performingarthroplasty, the reamer comprising: a first cutting structure having aninner concave surface that defines a first cavity and terminatesdistally in a generally circular leading edge, the leading edgeincluding a first cutting feature; an elongate member extending from thefirst cutting structure into the first cavity and toward the leadingedge, the elongate member including a second cutting feature, the secondcutting feature being located at least partially within the firstcavity; and a second cutting structure secured to said elongate memberand positioned within the first cavity, the second cutting structureextending outwardly from the elongate member toward the inner concavesurface and including a third cutting feature, wherein the first cuttingstructure includes a plurality of openings that are spaced apart fromthe leading edge and that extend through the inner concave surface, eachof the openings having a cutting edge.
 13. The reamer of claim 12,wherein the leading edge includes a plurality of cutting teeth.
 14. Thereamer of claim 12, wherein the second cutting feature comprises aplurality of flutes.
 15. A reamer for use in performing arthroplasty,the reamer comprising: a first cutting structure having an inner concavesurface that defines a first cavity and terminates distally in agenerally circular leading edge, the leading edge including a firstcutting feature; an elongate member extending from the first cuttingstructure into the first cavity and toward the leading edge, theelongate member including a second cutting feature, the second cuttingfeature being located at least partially within the first cavity; and asecond cutting structure secured to said elongate member and positionedwithin the first cavity, the second cutting structure extendingoutwardly from the elongate member toward the inner concave surface andincluding a third cutting feature, wherein the second cutting structurecomprises at least one cutting blade that extends outwardly from theelongate member.
 16. The reamer of claim 15, wherein the second cuttingstructure comprises a plurality of cutting blades that evenly spacedapart from each other around a circumference of the elongate member. 17.The reamer of claim 15, wherein the plurality of cutting blades arecantilevered from the elongate member.
 18. A reamer for use inperforming arthroplasty, the reamer comprising: a first cuttingstructure having an inner concave surface that defines a first cavityand terminates distally in a generally circular leading edge, theleading edge including a first cutting feature; an elongate memberextending from the first cutting structure into the first cavity andtoward the leading edge, the elongate member including a second cuttingfeature, the second cutting feature being located at least partiallywithin the first cavity; and a second cutting structure secured to saidelongate member and positioned within the first cavity, the secondcutting structure extending outwardly from the elongate member towardthe inner concave surface and including a third cutting feature, whereinthe second cutting structure is fixed to the elongate member, andwherein the elongate member is removably attached to the first cuttingstructure.